This invention relates to an ink jet printhead. More particularly, the invention relates to a fluidic seal for moving nozzle ink jet.
Most ink jet printheads of the type manufactured using micro-electro mechanical systems (MEMS) technology have been proposed in a construction using nozzle chambers formed in MEMS layers on the top of a substrate with nozzle chambers formed in the layers. Each chamber is provided with a movable paddle actuated by some form of actuator to force ink in a drop through the nozzle associated with the chamber upon receipt of an electrical signal to the actuator. Such a construction is typified by the disclosure in my International patent application Ser. No. PCT/AU99/00894.
The present invention stems from the realisation that there are advantages to be gained by dispensing with the paddles and causing ink drops to be forced from the nozzle by decreasing the size of the nozzle chamber. It has been realised that this can be achieved by causing the actuator to move the nozzle itself downwardly in the chamber thus dispensing with the paddle, simplifying construction and providing an environment which is less prone to the leakage of ink from the nozzle chamber.
According to the invention there is provided an ink jet printhead including: a plurality of nozzles each adapted to eject drops of ink toward a surface to be printed; wherein,
each of the nozzles having a nozzle chamber at least partially defined by an apertured roof portion operatively connected to an actuator such that the actuator moves the roof portion away from the surface to be printed to eject the ink; wherein,
the roof portion and the remainder of the nozzle chamber have structural features arranged in a combined geometry that cooperates with the surface tension of the ink to form an effective fluidic seal during normal operation of the printhead.
Preferably, the nozzle chamber is adapted to be supplied with ink via at least one conduit in an underlying substrate; and the roof portion has a sidewall depending from its periphery to telescopically engage a peripheral sidewall extending from an opposing floor portion to define the nozzle chamber such that the fluidic seal is formed between the overlapping sidewalls of the floor and roof portions.
Preferably, one of the telescopically interengaging sidewalls has a U-shaped cross-sectional configuration, comprising a proximal wall in close proximity to the other sidewall, and a distal wall substantially parallel to and spaced from the proximal wall, forming a channel between the proximal and distal walls.
Preferably, the sidewall depending from the periphery of the roof portion is located within the sidewall extending from the floor portion which has said U-shaped configuration, forming an open channel adapted to receive and contain ink therein.